SPF is a measure against UVB. It is not a timer, and doubling the number does not double the protection – the difference between SPF 30 and SPF 50 is far smaller than the numbers suggest. Look for broad spectrum if UVA matters to you, which it should.
The bigger variable is how much you put on. Most people apply a fraction of the amount used in testing, which means a bottle of SPF 30 applied thinly behaves like something considerably lower.
Apply generously before going out rather than once you are already in the sun, and reapply every couple of hours – and always after swimming or towelling, regardless of what the bottle says about being water resistant.
The places people miss are consistent: ears, the tops of feet, the back of the neck and the hairline. Nothing here lets you stay out indefinitely, and shade and covering up in the middle of the day do more than any cream.
Yaoh's are hemp-based and vegan, and Sol De Ibiza make a mineral formulation. Mineral filters sit on the skin rather than absorbing into it, which is why they can leave a faint white cast – that is the filter doing its job rather than a fault.
Aloe Pura's after-sun is for afterwards rather than instead. If skin is genuinely burnt and blistering, that is a pharmacy or GP matter rather than a lotion.
FAQ
Is SPF 50 twice as good as SPF 25?
No. The relationship is not linear and the difference at the top of the scale is much smaller than the numbers imply. How much you apply matters more.
How often should I reapply?
Every couple of hours, and always after swimming or drying yourself, whatever the bottle says about water resistance.
Why does mineral sun cream leave a white cast?
Mineral filters sit on the surface of the skin rather than absorbing. The cast is the filter itself and fades somewhat as it settles.
Does sun cream go out of date?
Yes. Check the date and the period-after-opening symbol, and replace last summer's bottle rather than trusting it.
